2Particulars•Problem: Pattern differ spatially•Solution: Spatial registration using SSD•Problem: Articulations vary in length, and thus, in number of frames.•Solution: Dynamic programming for temporal warping of sequences.•Problem: Features should have compact representation.•Solution: Principle Component Analysis.Feature Subspace Generation•Generate a lower dimension subspace onto which image sequences are projected to produce a vector of coefficients.• Components– Sample Matrix– Most Expressive Features